1. Field of the Invention
This invention relates generally to the field of optical recording apparatus and specifically to a high density optical recording apparatus adapted to provide a stabilized recording on a recording medium.
2. Description of the Prior Art
It is well-known that optical methods have been utilized as extremely effective methods for recording information of high density and for recording video signals.
However, in prosecution of optical recording as described above, it is required to have less than approximately 0.3.mu. of allowable clearance in positional relationship between the recording portion of the recording medium, which is formed in a drum, belt or disc and travels with respect to a recording optical system, and the recording optical system. In case the optical system secured with respect to the recording medium with conventional working accuracy is used, however, it is extremely difficult to maintain the relative position between the recording portion of the travelling recording medium and the recording optical system within such a small range of allowance as described above. Further, it is not easy to make sure that the recording medium is properly positioned with respect to the recording optical system, and to adjust the focus of the recording light.
In prosecution of optical recording, it is conventional to employ a floater adapted to be floated by fluid pressure generated between the recording optical system and the travelling recording medium, said floater being floated adjacent to said recording medium to thereby provide a method for maintaining the relative position within the range of allowance. Such a floating method and floating means are well-known as shown in, for example, IBM Journal Vol. 3, Nos. 3 (1959) pages 237 through 274, "A GAS FILM LUBRICATION STUDY". However, in maintaining the relative position by way of a single floater, when the whole mass and inertial moment are great and inclination is produced in an optical axis due to the undulation and the like formed on the surface of the recording medium, resistivity against it is not sufficient so that vibrations are continuously generated to thus produce an error in recording position and focus. Further, if the recording medium is specifically formed in a rotating disc, and when the recording optical system is moved in a radial direction, a travelling speed of the recording medium relative to the recording optical system is different depending upon the position in the radial direction so that the floating force of said floater is varied accordingly, thus it is difficult to maintain the relative position between the recording medium and the recording optical system.
Moreover, in case the recording optical system is floated merely by the single floater, there are many problems existed such as excessively great floating force, unstable floating space, accuracy in manufacture, and the like.